Beginner modeling question

[KWRMF197]

I'm working on a new mod that includes the use of the vanilla misc broken steel sword handle as a dagger. I've never done this before, and after swapping the models around in ck on a new duplicated steel dagger, I've found its completely invisible in my character's hands when I equip it. I know this has something to do with the mesh but I've not been able to find any material on this besides the in-depth, 45+ minute youtube videos on creating  completely custom weapons.

Unfortunately, as detailed as these videos are, there's a lot of info that doesn't pertain to this situation and im not sure what's pertinent and what's not. I would love if someone could give me the 5 year old version of the reason (or point me in the direction of a good guide) of why this happens and what has to be done to properly use skyrim's junk/misc models for weapons and even armors.

Thank you!

[AaronOfMpls]

Which view is it invisible in?  If I remember right, weapons need to have a "sitting around" model, an "in someone's hand, 3rd person" model, and an "in your hand, 1st person" model.  (I'll have to look in the CK later to see what those are called, specifically.)

[KWRMF197]

Pretty much every view. Tried equipping right, left, etc. Thank you for the info. Do you remember where I specify those things in ck? I only saw boxes for first person model and the general 3rd person on the weapon page.

[soupdragon1234]

Grab an original model dagger .nif and open it and the broken sword .nif and delete the BS/NiTriShapes from the dagger  and replace with the one from the sword

[KWRMF197]

Thank you soupdragon! I couldn't find any info anywhere that that's what I needed to do lol

[scorrp10]

With weapons, there seems to be a fairly specific mesh naming requirement in order for things to work properly, i.e. 

Actual weapon needs to derive from the root, scabbard mesh (visible only when weapon is sheathed), and the blood overlay meshes all require specific naming.    And indeed, for first person, I had to create a practically identical mesh where only difference is in mesh naming.

And 

[KWRMF197]

18 hours ago, scorrp10 said:

With weapons, there seems to be a fairly specific mesh naming requirement in order for things to work properly, i.e. 

Actual weapon needs to derive from the root, scabbard mesh (visible only when weapon is sheathed), and the blood overlay meshes all require specific naming.    And indeed, for first person, I had to create a practically identical mesh where only difference is in mesh naming.

And 

I have to say I definitely wasn't anticipating all this for a model swap lol. Thanks a lot! This helps tremendously!